When it comes to traditional and solid-state lighting devices, enclosures made of glass are still the most economical ones. However, because of some unsolved challenges in glass and in particular in glass based light tubes, the use of costly plastic tubes and end-caps has become rather wide spread. A first problem with plastic tubes is that they are more expensive than glass. A second problem with plastic tubes is that an asymmetric temperature distribution across the tube height and/or length will and does cause warp, deforms the tube permanently. To avoid the problem of warping some plastic tubes do come with build-in material pre-stress (in the opposing direction) causing the tubes to straighten on operation. Furthermore, the look and feel of plastic is inferior to that of glass.
The key problem with the highly appreciated glass is that it can only be worked at high temperature, say above 1200° C. Hence, when delicate electronics components come too close to the hot glass, severe and irreversible degradation is eminent. With the high temperatures required during the joining of the glass pieces being the key issue, there is a need to allow for the pre-sealing insertion of fragile electronics components into the glass body and/or to shield them from the high temperatures during the glass joining and in a cost effective manner.